1. Field of the Invention
This invention relates to a process of microinjecting liquids or suspensions of substances into living cells by means of a movably mounted cannula and a stage, wherein the cannula extends at an oblique angle to the stage, the cannula and the stage are adjustable relative to each other in two directions (X, Y) in a plane which is parallel to the stage, and the cannula is also movable in a direction Z, which is at right angles to the plane that is defined by the directions X and Y.
This invention relates also to an apparatus for carrying out the process, which apparatus comprises a holder for the cannula.
The term cannula includes also capillary tubes or microcapillary tubes.
2. Description of the Prior Art
In connection with such processes it has already been endeavored to achieve a certain mechanization in that a cannula which has been adjusted to be inclined from the vertical or to the stage is disposed above and aligned with a cell and is vertically lowered and this is accompanied by an observation under a microscope. In that operation, problems will arise in connection with the detection of the position of a cannula or capillary tube in the direction Z. It must also be taken into account that it is not always intended in microinjection technology to inject into the core of a cell even though an injection can be made into the core in other cases. In the known embodiments it is possible only to make a rough assessment of the location at which a puncture is to be made. The vertical downward movement involves the disadvantage that the cannula is forced into the cell by a movement having a considerable lateral component so that the membrane of the cell will be torn to form an elongate slit. This may result in irreversible damage to the cell membrane, i.e., to the cell as a whole. Besides, a cannula may break.
It is also known to use a stage which consists of the stage of a microscope and so to arrange a holder for the cannula that the tip of the cannula lies in the direction of observation and an exact observation is ensured in that the microscope is exactly focussed to the tip.
Such a stage which is a part of a microscope may consist of a known compound stage, which is adjustable relative to the objective. In that case, one cell or more cells of a large number of cells of a cell culture can be moved on the compound stage into the field of view of the microscope.
From that aspect a preferred embodiment of the invention is based on the assumption that numerous cells in a certain arrangement, e.g., in a special cell culture vessel, are provided on the compound stage and each cell can individually be positioned.
The known devices used for that purpose are highly expensive and under the control of a computer operate an automatically controllable compound stage to align one cell at a time with the cannula in accordance with a predetermined pattern.
Numerous means for controlling the cannula by computerized image-processing techniques could be conceived but would require a provision of relatively expensive additional means for controlling the movement of the microscope stage relative to the tip of the cannula.